This grant proposes an innovative approach to prevent low back pain and injury associated with prolonged seating. Specifically, we propose to integrate lumbar extensor muscle strengthening with ergonomic task seating. By doing so, we will provide the public with a means to address two primary causes of low back pain and injury: 1) poor or prolonged seating postures, and 2) weak lumbar muscles, and to do so without leaving the workplace. With over 100 million American workers sitting on the job, work styles becoming more sedentary, and the average worker getting older, the need for preventive measures is critical. Over 100 million work days are lost each year due to low back pain, second only to the common cold. Medical treatment costs for employers exceed $26 billion per year; costs related to lost productivity and retraining new employees exceed $100 billion per year. [unreadable] Leveraging our preliminary work on the mechanical hardware, Phase I will develop the technology required for independent and safe performance of the exercise regimen and test the efficacy of the exercise stimulus to isolate the lumbar extensors via a novel method of pelvic stabilization. Specific Aim 1 will develop a computerized visual feedback system for inclusion on the chair to monitor user performance during exercise. Specific Aim 2 will evaluate and compare lumbar extensor surface electromyographic (EMG) activity during dynamic trunk extension exercise on two devices; our prototypic Back-to-Work ChairTM, and the clinically proven MedXTM Lumbar Extension machine (MedX Corporation, Ocala, FL). Successful completion of this work will position us in Phase II to subject the chair to clinical validation in a workplace environment. This would include usability testing with seated workers to optimize the ease of use and content of the computer feedback system, and a 12 week program of progressive resistance exercise to determine the effect of isolated lumbar strengthening on reports of low back pain and morphological changes of the lumbar spine. [unreadable] [unreadable]